Major depressive disorder (MDD) is a highly prevalent and debilitating condition that reduces quality of life, increases health care utilization, markedly impairs social/occupational functioning, and enhances suicide risk for countless individuals worldwide. A substantial proportion of MDD patients present with comorbid insomnia that significantly complicates their clinical management. For many such patients, insomnia represents a longstanding and problematic condition that predates the onset of MDD, adds to their suicide risk, dampens their response to traditional depression treatment, and enhances the likelihood for MDD relapse. Moreover, many patients who show remission of depressive symptoms with traditional therapies (e.g., antidepressant medications, cognitive therapy) suffer from residual insomnia that increases their chances for eventual relapse. Despite the deleterious effects insomnia may have on MDD patients, there has been surprisingly little research to test effective insomnia management strategies among this patient group. Some reports suggest that depression treatments may benefit from adding a hypnotic medication to traditional depression therapy, but this approach has it limits since sleep improvements achieved with hypnotics do not endure after hypnotic discontinuation. Cognitive-Behavioral Insomnia Therapy (CBT-I) represents a promising alternative treatment for MDD since it is highly effective and produces sleep improvements that persist well beyond the discontinuation of acute therapy. Unfortunately CBT-I has yet to be tested among MDD patients with comorbid insomnia. In the current project, we will conduct a randomized clinical trial to test the efficacy of CBT-I when used in isolation or in combination with antidepressant medication (escitalopram) among MDD patients with comorbid insomnia. A sample of 201 patients with MDD and comorbid insomnia will be randomized to treatments consisting of the combination of antidepressant medication plus CBT-I, antidepressant medication plus placebo behavioral insomnia therapy, or CBT-I plus a placebo medication. Objective (polysomnography, actigraph) and subjective (sleep diary, questionnaires) sleep measures, as well as depression and quality of life measures will be obtained before therapy, after an 8-week treatment phase, and at 6-months follow-up. Results of this trial will provide important new information about the short and long-term management of those highly challenging and difficult to treat patients with insomnia comorbid to MDD. Our long-term objective is commensurate with The National Sleep Disorders Research Plan, as well as recommendations emanating from the National Institutes of Health State of the Science for Insomnia Conference Statement regarding the need for treating the insomnia of under-serviced populations. The resultant public health benefits from the proposed study include improved sleep, mood, well-being, and corollary medical and psychiatric conditions for depressed patients with insomnia.